The correct method to make a Cloud Storage bucket public is by assigning the Storage Object Viewer role to allUsers. This ensures that anyone on the internet can access the static web assets without authentication. The option to use allAuthenticatedUsers (Option B) restricts access to only authenticated users, which does not meet the requirement for public access. There is no 'make public' checkbox in the GCP Console (Option D) or a gsutil make-public command (Option A) available for this purpose. For detailed steps, refer to the GCP documentation on sharing files in Cloud Storage, which guides on making groups of objects publicly readable.